U.S. Pat. No. 4,508,842 discloses a highly active vanadium-containing catalyst system suitable for producing ethylene polymers comprising:
(A) a solid catalyst component consisting essentially of PA0 (B) an alkylaluminum cocatalyst, and PA0 (C) a halohydrocarbon polymerization promoter. PA0 (A) a solid catalyst component containing: PA0 (B) a trialkylaluminum cocatalyst. PA0 (1) a solid catalyst component obtained by precipitating vanadium trihalide from an ether solution onto a silica and/or alumina carrier and then treating the product with an alkylaluminum, PA0 (2) an alkylaluminum, PA0 (3) an alkyl halide, and PA0 (4) an alkoxy compound of silicon. PA0 (A) a solid catalyst component consisting essentially of PA0 (B) a triethylaluminum cocatalyst, PA0 (C) a halohydrocarbon polymerization promoter, and PA0 (D) a boron alkoxide activity enhancer having the formula: EQU R.sub.n B(OR.sup.1).sub.3-n PA0 (1) a solid, particulate, porous inorganic carrier, as support for PA0 (2) the reaction product of (a) a vanadium trihalide and (b) an electron donor, and PA0 (3) a boron halide or alkylaluminum modifier. PA0 (1) the reaction product of (a) a vanadium trihalide and (b) an electron donor, and PA0 (2) a boron halide or alkylaluminum modifier.
(1) an inorganic carrier, as support for PA1 (2) the reaction product of (a) a vanadium trihalide and (b) an electron donor, and PA1 (3) a boron halide or alkylaluminum modifier, PA1 (a) a vanadium compound, PA1 (b) an organometallic compound of a metal of Group III of the periodic table, and PA1 (c) an inorganic oxide support, and PA1 (1) a solid, particulate, porous inorganic carrier, as support for PA1 (2) the reaction product of (a) a vanadium trihalide and (b) an electron donor, and PA1 (3) a boron halide or alkyl-aluminum modifier, PA1 R and R.sup.1 are alkyl radicals containing from 1 to 14 carbon atoms, which radicals may be the same or different, and PA1 n is an integer having a value of 0, 1 or 2. PA1 M is boron or AlR.sup.2.sub.(3-a) wherein each R.sup.2 is an alkyl radical containing from 1 to 14 carbon atoms, which radicals may be the same or different, PA1 X is selected from the group consisting of fluorine, chlorine, bromine and iodine, and mixtures thereof, and PA1 a is an integer having a value of 0, 1 or 2, provided that a is 3 when M is boron. PA1 R.sup.3 is hydrogen or an unsubstituted or halosubstituted alkyl radical containing from 1 to 6 carbon atoms, which radicals may be the same or different, PA1 X' is halogen, and PA1 b is 0, 1 or 2. PA1 R and R.sup.1 are alkyl radicals containing from 1 to 14 carbon atoms, which radicals may be the same or different, and PA1 n is an integer having a value of 0, 1 or 2.
U.S. Pat. No. 4,426,317 also discloses a vanadium-containing catalyst system for polymerizing ethylene, said catalyst system comprising:
According to this reference, the organoaluminum compound must be reacted with the inorganic oxide support.
Japanese Public Disclosure No. 62-25112 (Application Ser. No. 60-163525) likewise discloses a vanadium-containing catalyst composition useful in the Preparation of ethylene Polymers. Such position consists of:
Unfortunately, the presence of the alkoxysilicon compound in such composition has been found to adversely affect polymer productivity.